A current favorite is that the Kremlin has ''given up on Ronald Reagan.'' It's a reading that various Soviet spokesmen have been leaking to visiting Westerners. And it jibes nicely with longtime Kremlin efforts to encourage European pressure for a mellowing of US rhetoric.

Another popular theory is that any mixed signals emanating from Moscow can best be ascribed to the process of political transition from the 18-year rule of Soviet President Leonid Brezhnev. No one is really in charge here anymore, the argument goes, so you end up with either incoherent foreign policy or no policy at all.

Yet at least one recent move by Moscow - its negotiating proposal for ''deep'' strategic arms cuts of the sort rejected when the Carter administration proposed them in 1977 - illustrates the danger of jumping to simplistic explanations.

A Western diplomat familiar with the details of the Soviet proposal tabled at the Geneva talks remarks: ''We had expected neither so serious a proposal, nor such an early one. Arms policy is an area that obviously requires balancing of powerful interest groups, and priorities, at home. The Geneva talks suggest that , transition aside, the Soviets remain both interested in, and capable of, substantive dealings in foreign policy.''

Lengthy private conversations with six senior Soviet officials, four of them with regular access to members of the ruling Communist Politburo and Secretariat , suggest that US policy since the invasion of Afghanistan, and particularly since President Reagan's inauguration, have prompted a sharp debate here on how best to respond.

The debate may touch on a wide range of problems, from the framing of public statements to the presentation of arms proposals, from the handling of internal dissidence to assembly of a strategy on East-West trade. The process brings into play not only political calculations but also simple human nature. Constantly in the background, meanwhile, are very real practical constraints on Soviet action.

The human-nature factor consists largely of the uneasy suspicion among senior officials here that their nation, despite its steel mills and nuclear weaponry, is somehow not fully a superpower. Facing economic woes at home, among them the current inability to come up with desired stocks of meat and dairy products for 270 million citizens, aware of a technology lag with both economic and military implications, the Soviets are feeling decidedly insecure nowadays.

More to the point, the Soviets sense in the toughened US stance since Moscow's troop move into Afghanistan a renewed signal that Americans do not take Soviet superpower seriously. Instead, the Americans are seen as seeking actively to flaunt their superiority, almost to beat the Soviets over the head with it, to publicly challenge and to embarrass them.

Thus, no matter how genuinely concerned Moscow is over specific US policy decisions like the Reagan administration's move for heightened arms spending, private comments from senior officials suggest a deeper resentment of the overall thrust of American policy - its tone.

This feeling has become particularly notable since Mr. Reagan declared before the British Parliament last summer that communism was bound to end up on the ''ash heap of history.''

Western diplomats are quick to scoff that, when it comes to rhetoric, ''The Soviets can dish it out, but they can't take it.'' This happens to be true, but it need not make the Soviet response any less genuine.

Shortly after the Reagan remarks, a prominent member of the Communist Party's Central Committee reviewed, in a lengthy conversation with the Monitor, prospects for a strategic arms accord in Geneva.

In theory, he suggested, Mr. Reagan's opening proposal need not preclude an agreement, notwithstanding the Soviets' propaganda assault to the contrary.

'But the problem is deeper,'' he went on. ''It is a problem of the overall principles of American relations with us. . . . Everything points to the fact that Reagan wants to bleed us white, to squeeze us on all fronts, military, trade, technology. . . .''

Against this background, a central focus of the Soviets' search for a counterstrategy has been to signal publicly that ''Ronald Reagan can't kick us around.''

The perceived need here has been for a convincing show of superpowerdom. The problem - in some ways a thornier one than responding, for instance, to specific US trade sanctions - has been that such a demonstration is much easier sought than done.

Nevertheless, the impulse must be kept in mind in tracing recent specific moves in Soviet-American relations. At this writing, the score card, in various key areas, looks roughly like this:

Arms policy. On the two major issues of the hour, strategic nuclear weaponry and shorter-range nuclear weapons in the European theater, the Soviets have publicly pushed for the twin negotiating processes now under way in Geneva.

On strategic arms, the Soviets have so far flatly rejected the Reagan administration's proposal for grouped cutbacks that would most heavily affect the land-based missiles on which Moscow relies to a greater extent than does Washington.

In reply, diplomats report, Moscow has suggested a SALT II-type accord involving significantly greater reductions than the unratified 1979 agreement. A recent report in the Los Angeles Times quotes US analysts as saying the Soviet proposal seems implicitly to accept Mr. Reagan's insistence on a parallel limit on missile warheads.

On European-theater weaponry, the Soviets have stood firm on a proposal that would in effect leave their recently installed force of triple-headed European missiles intact, while barring deployment of new US weapons that Western governments intend as a balance to the Soviet force.

Although at least one senior Soviet official, in an interview with the Monitor, has spoken of an eventual compromise between the Soviet and Western positions, it seems unlikely Moscow will show its full hand in Geneva much before the planned deployment, controversial in West Europe, of the new US missiles in late 1983.

If less noticeably, however, the Soviets have also sent some rather more defiant signals outside the dual arms talks.

In a speech last spring, President Brezhnev warned that if the new US missile deployment did go ahead, the Kremlin would be forced to take ''retaliatory steps'' placing US territory ''in an analogous position.''

A senior official here says the Soviets are pushing hard to develop a radar-elusive cruise missile comparable to that assembled by the Americans, and that a sea-based cruise force is considered the most likely way of making good on Mr. Brezhnev's warning.

Another official, Central Committee member and foreign policy specialist Nikolai Inozemtsev, singled out the Brezhnev statement as one ''practical'' sign of general Soviet resentment toward Reagan administration policy.

Mr. Inozemtsev, who recently passed on, added: ''These (Brezhnev) remarks were not just words, but refer to serious . . . measures that can and will be undertaken. This is not just an empty threat.''

More generally, various Soviet officials have signaled that new US strategic arms plans and the eventual deployment of new US missiles in Europe could prod Moscow formally to adopt a policy of ''launch on warning'' of an enemy missile firing. A senior official says this would ''turn everything over to the computers.''

The official suggested that he, and colleagues, retain serious misgivings about this, fearing that an accidental nuclear exchange could result, but that the Americans, in effect, should be made to realize that they risk perilously raising the stakes of the superpower arms race.

Soviet-Western trade. In the wake of President Carter's 1980 grain restrictions, Moscow sought imports elsewhere, from Argentina, Australia, Canada , Brazil. When President Reagan moved more recently to embargo US equipment and technology for a planned Siberia-West Europe gas pipeline, the Soviets ostentatiously stepped up efforts to produce domestic equivalents.

In theory, senior Soviet officials say, Moscow is determined to reply to the US restrictions with a concerted shift away from American imports.

An economic specialist said that in nonagricultural imports, where Western Europe and Japan already play a greater role than does the US, the trend could be expected to intensify. He said there also appeared to be growing support within the Soviet policy establishment to move away from ''purchasing ready-made equipment, in favor of buying licenses, technology, and perfect this'' domestically. ''Also, we will probably buy more complete plants - turnkey operations.''

But both he and other officials, while considering such a shift an important signal to Washington, said they were fully aware of the practical limitations. Thus, although Soviet grain purchases from the US remained a far smaller portion of overall Soviet imports than before the Carter restrictions, grain trade with the US was continuing.

Thus the response to other US trade limitations could not be a major and general swing away from foreign technology, as some in Moscow were said to favor , but rather a shift toward further substitution of non-American imports.

The Middle East. Here, as in other third-world crisis points since the Afghan invasion, the general line has been one of caution, in the sense that the Soviets have steered clear of direct involvement.

Yet the current Mideast crisis provides the best single example of the various, sometimes contradictory, impulses now governing overall Soviet policy toward the Americans.

From the outset of Israel's June blitz through southern Lebanon to the outskirts of Beirut, senior officials have signaled privately Moscow's fundamental reluctance to encourage a widening of the conflict.

There were excellent practical reasons for this reluctance, beyond what officials suggested was an underlying concern not to risk a round of nuclear saber rattling with Washington. As one official put it, straightforwardly, the Soviet-armed Syrians and Palestinians were simply in no position on the ground credibly to pursue a showdown with the Israeli force.

Yet as Washington moved to mediate a resolution of the crisis with what Soviet officials saw as purposeful disregard of any Kremlin input, pressure here mounted for a Kremlin show of superpowerdom. This, implied a senior official who added at the time he personally opposed the move, explained President Brezhnev's July warning that if a US troop contingent landed in Beirut, ''The Soviet Union would build its policy with due consideration of this fact.''

Some two weeks later, Mr. Breznev was quoted in Pravda as saying, ''We will continue to oppose categorically the appearance of American forces on Lebanese soil. We have given a warning to this effect.''

At the time of the first warning, the Soviets well knew that a US troop contingent was a real possibility that Moscow neither could nor would move to prevent. This was doubly so at the time of the repeated warning in late July. But, said the official who thought the warning unwise, ''We have to show the image of a superpower.'' (At this writing, the Soviets have reacted much more cautiously to the announced return of US, Italian, and French troops to Beirut, although having called for dispatch of a United Nations force instead.)

In the months ahead, overall Soviet policy toward the Reagan administration seems likely to include further moves to ''demonstrate superpowerdom,'' to produce outward and visible signs of Kremlin resentment. On the other side of the scales remain the practical limitations of domestic and world politics and, so far at least, an abiding Kremlin desire to salvage the arms-negotiation process and, ideally, to revive the more comfortable climate of Nixon-era relations with Washington.

One relatively inexpensive means of showing Soviet resentment, a near-total rejection of Jews' applications for exit visas, seems sure to continue meanwhile. Officials leave little doubt of a degree of ''linkage'' between the two phenomena.

Some Western diplomats see a recently intensified Soviet crackdown on dissidence as part of the same equation, but such a connection is impossible for a foreign reporter here to determine with any certainty.

Whether the Soviet-American quarrel might turn violent (presumably by proxy, in the third world) is also necessarily a matter of speculation. Senior Soviet officials interviewed by the Monitor reject the American contention that it was Moscow, in invading Afghanistan, that did most to harden the American policy line.

But in their own version of the Americans' insistence on ''linkage' in superpower relations, various officials counter by arguing that had ties with Washington been better, the Afghan incursion might have been less likely.

Asked whether, as a Soviet defector has maintained, the 1975 dispatch of Cuban troops to Angola was Moscow's reply to the first great crack in detente (the Americans making most-favored-nation status for the Soviets conditional on freer Jewish emigration), one official replied:''

If Soviet-American relations had been stronger, it is possible, probable, there would have been no Cubans in Angola. . . . There is no direct link. But generally, bad relations (between the superpowers) contribute to an environment where critical options, like the Cubans in Angola or us in Afghanistan, are used.''

This and other senior officials, meanwhile, rejected as facile the idea that Moscow had somehow ''given up'' on prospects for better superpower relations during the Reagan administration, despite selective Soviet leaks to the contrary. At least so far, the officials said, the Soviet vision of ''detente'' remained intact.

The official added that he felt American analysts tended to give a backward assessments of the impact of Kremlin transition on relations with Washington. At present, he said, the main danger was that ''prospects for relations will be far worse if they are already bad when transition occurs.''

It is natural that transition anywhere carries with it difficulties, and that foreign policy is naturally deemphasized. There are other concerns, internal ones . . . unless there is a momentum in relations at the time, it is inevitable , at least, that valuable time will be lost.''